Two compartment frost-free refrigerator



Oct. 17, 1961 lmJ.MANN ETAL TWO COMPARTMENT FROST-FREE REFRIGERATORFiled July 8, 1960 2 Sheets-Sheet 1 64 X 38 f 60 so 66 n}; 40 92 I zg jla5, 22 ea so -ss so 58 Fig. HVVENTURS Leonard J. Mann By John JO'Connell Their Attorney Oct. 17, 1961 L. J. MANN E TAL TWO COMPARTMENTFROST-FREE REFRIGERATOR Filed July 8, 1960 2 Sheets-Sheet 2 Fig. 3

INVENTORS Leonard J. Mann Y John JOConna/l T/reir Af/orney 3,004,400Patented Oct. 17, 1961 3,004,400 TWO COMPARTMENT FROST-FREE REFRIGERATORLeonard J. Mann and John J. OConnell, Dayton, Ohio, asslgnors to GeneralMotors Corporation, Detroit,

Mrch., a corporation of Delaware Filed July 8, 1960, Ser. No. 41,638 4Claims. (Cl. 62-156) Refrigerators are popular which are free of frostin thefood storage compartments. Because of the high selling price, theyare limited to those having larger incomes. In such refrigerators, frostaccumulates rapidly upon the colder evaporator. 'It is customary toprovide an expensive clock defrosting device for periodically stoppingthe refrigerating system and using an electric heater to heat thisevaporator during such a period to defrost it. This is inelficient sincethe electric heat uses energy in removing frost created by the previousexpenditure of energy in making refrigeration.

It is an object of this invention to provide a simple economicalrefrigeration'and defrosting system for a frost free refrigerator.

It is another object of this invention to provide a simple refrigerationsystem in which the frost on the colder evaporator is removed every offcycle by the relatively warmer air circulated from the above freezingcompartment.

It is another object of this invention to provide a refngerating systemin which the air from the below freezmg compartment is circulated inheat transfer relation with the colder evaporator which therebyaccumulates frost while the air from the above freezing compartment iscirculated in heat' transfer relation with the warmer evaporator duringthe refrigeration cycle but during the off cycle the warmer air from theabove freezing compartmentis circulated in heat transfer relation withthe colder evaporator to defrost it.

These'and other objects are attained in the form shown in the drawingsin which one of the vertical walls of the insulated refrigerator cabinetis provided with an evapo rator compartment having supply and returnpassages extending thereto from the upper, below freezing compartment.Shorter passages connect directly with the above freezing compartment.The above freezing compartment is also provided with an evaporatoroperating at all times above freezing temperatures which. reduces therequired size of the first mentioned colder evaporator operating belowfreezing temperatures and accumulating frost during the refrigeratingcycle. During the refrigerating cycle, a damper means closes thecommunication between the evaporator compartment and the abovefreezingcompartment, and a continuously operating blower circulates air betweenthe below freezing evaporator and the evaporator compartment containingthe colder evaporator to keep the below freezing compartment cold whilefrost accumulates upon this colder evaporator.

A simple thermostatic switch operating upon a defrosting cycle inresponse to the temperature of the colder evaporator stops the operationof the refrigerating system at a predetermined low temperature thereofand starts it only after it has attained a temperature above freezingsoas to insure its defrosting. This switch also controls theelectrically operated damper so that, during the refrigerating cycle,the passages to the above freezing compartment are closed andcirculation between the colder evaporator in the evaporator compartmentand the below freezing compartment is assured. During the off cycleunder the control of this thermostatic switch, the electrically operateddamper is moved to open the passages to the above freezing compartmentand to close the passages leading to the below freezing compartment sothat the warmer air from the above freezing compartment circulates bythe continuously operating fan over the colder evaporator to heat theevaporator to a point at which the frost thereon is melted and removedby the circulating air. The fan motor for the warmer evaporator isstopped by being connected in parallel with the compressor motor of therefrigerating system during the off cycle.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the drawings:

FIGURE 1 is a vertical transverse front sectional view of a frost freerefrigerator embodying one form of our invention;

FIGURE 2 is a side sectional view taken along the line 22 of FIGURE 1;

FIGURE 3 is a wiring diagram for the system shown in FIGURES l and 2;and

FIGURE 4 is a diagram of one form of refrigerating system for the systemshown in FIGURES 1 and 2.

Referring now to the drawings, there is shown an insulated refrigeratorcabinet 2-0 provided with vertical insulated side walls 22, an insulatedtop wall 24, an insu lated bottom wall 26, an insulated rear wall 28 anda horizontal insulated dividing wall 30 dividing the interior of thecabinet into an upper, below freezing compartment 32 and a lower, abovefreezing compartment 34. .A door .36 completes the enclosure of thecompartments.

In the right side wall 22, there is provided a centrally locatedevaporator compartment 38 containing the colder evaporator 40. A coldair evaporator discharge duct 42 extends upwardly from the evaporatorcompartment 38 and discharges through an outlet 44 into the upperportion of the below freezing compartment 32 which is maintained atabout 0 F. The air leaves the below freezing compartment 32 through twooutlets 46 located on opposite sides of the evaporator air dischargeduct 42 which connect with evaporator inlet ducts 48 extendingdownwardly on opposite sides of the evaporator compartment 38 to asemicircularair chamber 50 which connects with the inlet 52 of the fan54 driven by an electric motor 56. The fan 54 is located in a separatescroll 58 which discharges into the bottom of the centrally locatedevaporator compartment 38.

The inner liner 60 of the above freezing compartment 34 is provided withtwo openings 62 in the right side wall 22 connecting directly with thedual evaporator inlet ducts 48. This right side wall 22 is also providedwith an opening 64 connecting with the top portion of the evaporatorchamber 3-8 immediately above the evaporator 40 as shown in FIGURE 2.Thus, each compartment has two openings connecting with the downwardlyextending evaporator inlet ducts 48. Also, each compartment has anopening connecting with the upper portion of the evaporator chamber 38.

To carry out our invention, we provide an electrically operated dampermeans, designated by the reference character 66, shown in the full lineposition in FIGURE 1 closing the openings 62 and 64 in the inner liner60 of the above freezing compartment 34. The dotted line position 68 isalso shown in FIGURE 1 in which the damper 66 closes the evaporatordischarge and inlet ducts 42 and 48 to shut off communication betweenthe below freezing compartment 32 and the evaporator compartment 38. Thedamper 66 is shown as operated by a pinion 70 and a rack 72 operated bythe solenoid 74 in a circuit 76 connected in parallel with thecompressor motor 78 and the motor 80 which drives a fan 82 forcirculating air through a warmer evaporator 84 located.

of the colder evaporator 40. These three circuits are connected inparallel with a thermostatic snap-acting switch 86 having a bulb 88mounted upon a lower portion of the evaporator 40 and adjusted tooperate upon a defrosting cycle. Preferably, this switch '86 opens whenthe evaporator 46 reaches a defrosting temperature, such as 36 F., andcloses when the evaporator 40 reaches a temperature of -l2 F. This willmaintain an average temperature of about F. in the below freezingcompartment 32.

When the switch 36 is closed, the fan 82 operates to cool the abovefreezing compartment 34 by drawing air in through the fan inlet 90 inthe baffle 92 and discharging the air through a scroll 94 connectingwith the bottom of the evaporator 84 for discharging air upwardly behindthe baffle 92 into the upper part of the above freezing compartment 34.The closing of the switch 86 also causes operation of the compressormotor 78 and energizes the electromagnet 74 so as to move the damper 66from its dotted line position 68 to its full line position as shown inFIGURES 1 and 3; Connected in series with the solenoid 74 is a bimetalswitch 93', preferably located in the evaporator compartment 38 and setto a close at 15 B, so as to insure that no warm air will be deliveredto the below freezing compartment 32. The fan motor 56 is connecteddirectly across the supply conductors L and L and operates continuouslyto circulate air through the evaporator 40 at all times.

The evaporator 84 preferably operates at a temperature of about 33 F.maintained by means of a restrictor line 127 between the evaporator 84and the evaporator 40 so that it never accumulates any frost. Therefore,

this evaporator does not need to be defrosted at any time;

The provision of the two evaporators makes it possible for each of theevaporators to be relatively small and also makes it possible to rapidlydefrost the colder evaporator 40. This is accomplished when the colderevaporator 40 reaches the cut-off point of l2 F. and opens the switch86. This not only stops the compressor motor 78 and the fan 82 but italso deenergizes the solenoid 74 which thereby moves the damper 66 fromthe full line position to the dotted line position, indicated by thereference character 687 As long as the switch 86 remains in the openposition, air will be drawn from the above freezing compartment 34 whichis at about 36 F. in through the openings 62 in the inner liner 6% anddown through the evaporator inlet ducts 48 into the inlet 52 of the fan54 which discharges the air through the evaporator 40 to warm theevaporator rapidly and remove the frost therefrom, after which the airis discharged back into the above freezing compartment 34 through theevaporator compartment 38 and the discharge opening 64. This maintainsthe above freezing compartment 34 at a relatively cool temperature. Thiscirculation continues until the evaporator 40 rises above the freezingtemperature to completely melt any frost thereon. Because of the highvolume of air circulated over the surfaces of the evaporator 40 from theabove freezing compartment 34 at the temperature of about 36 F., thedefrosting is rapid and the evaporator 49 rapidly reaches the cut-ontemperature of 36. This is sufiiciently rapid that the compartment 32which is disconnected from the evaporator compartment 38 and theopenings 44 and 46 during the off cycle does not substantially rise intemperature.

The reclosing of the switch 36 first resumes operation of the compressormotor 78 and the refrigerating system and, subsequently, upon theclosing of the thermostat 5 3, causes the movement of the damper 66 fromthe dotted line position 68 to the full line position. This restores thenormal refrigeration cycle to lower the temperature in the belowfreezing compartment as well as in the above freezing compartment 34.The evaporators 40 and 84 are connected in series in an arrangementcapable of maintaining the desired temperature differences; As

shown in FIGURE 4, the motor 78 drives a compressor 121 discharging intoa condenser 123 which connects through a long restrictor 125 with thewarmer evaporator 84 while a shorter restrictor12-7 connects with thecolder evaporator 40. The outlet of the evaporator 40 connects throughthe suction conduit 129 with the compressor 121.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows: 7

1. Refrigerating apparatus including insulated walls enclosing an abovefreezing compartment and a below freezing compartment, said insulatedwalls being provided with at below freezing evaporatorcompartment, acold evaporator located in said evaporator compartment, means forming insaid insulated walls an air circuit connecting said below freezingcompartment and said evaporator compartment, an above freezingevaporator located in heat transfer relation withsaid above freezingcompartment, means providing communication between said evaporatorcompartment and said above freezing compartment, damper means forshutting oif communication from said evaporator compartment alternatelywith said above freezing and below freezing compartments, fan means forforcibly circulating air alternately from said below and above freezingcompartments through said evaporator compartment in heat transferrelation with said below freezing evaporator and return to said belowand above freezing compartments alternately, and means for stoppingrefrigeration in said below freezing evaporator during the timecommunication is shut ofi between said below freezing and evaporatorcompartments.

2. Refrigerating apparatus including insulated walls enclosing an abovefreezing compartment and a below freezing compartment, said insulatedwalls being provided with a below freezing evaporator compartment, acold evaporator located in said evaporator compartment, means forming insaid insulated walls an air circuit connecting said below freezingcompartment and said evaporator compartment, an above freezingevaporator located in heat transfer relation with said above freezingcompartment, means providing communication between said evaporatorcompartment and said above freezing compartment, damper means forshutting off communication from said evaporator compartment alternatelywith said above freezing and below freezing compartments, fan means forforcibly circulating air alternately from said below and above freezingcompartments through said evaporator compartment in heat transferrelation with said below freezing evaporator and return to said belowand above freezing compartments alternately, refrigerant liquefyingmeans operably connected to said below and above freezing evaporators,and a thermostatic control operating upon a defrosting cycle andresponsive to the temperature of said cold evaporator for starting theoperation of said liquefying means and moving said damper means to shutoff communication with said above freezing compartment after said coldevaporator reaches a temperature'above freezing and for stopping theoperation of said liquefying means and moving said damper means to shutoff communication with said below freezing compartment after said coldevaporator reaches a predetermined temperature below freezing.

3. Refrigerating apparatus including insulated vertical walls andinsulated horizontal walls enclosing an above freezing compartment and abelow freezing compartment, one of the vertical walls adjacent the abovefreezing compartment being provided with an evaporator compartment andsupply and return passages extending from said evaporator compartment tosaid above and below freezing compartments, a cold evaporator located insaid evaporator compartment, a second evaporator upon one of thevertical walls in the above freezing compartment, a

refrigerant liquefying means operably connected to said evaporators andoperable to cool said cold evaporator to below freezing temperatures andto cool said second evaporator to above freezing temperatures, dampermeans having a first alternate position for shutting olf communicationbetween said evaporator compartment and said below freezing compartmentand a second position for shutting off communication between saidevaporator compartment and said above freezing compartment, fan meansfor circulating air through said evaporator compartment and saidpassages and said below and above freezing compartments in accordancewith the position of said damper means, and control means having oneposition for operating said liquefying means to cool said coldevaporator to below freezing temperatures to cause frost to form thereonand to cool said second evaporator to above freezing temperatures andsetting said damper means in said second position and having anotherposition for stopping the operation of said liquefying means and settingsaid damper means in said first position to cause the circulation of airbetween said above freezing compartment and said evaporator compartmentto quickly defrost said cold evaporator.

4. Refrigerating apparatus including insulated vertical walls andinsulated horizontal walls enclosing an above freezing compartment and abelow freezing compartment, one of the vertical walls adjacent the abovefreezing compartment being provided with an evaporator compartment andsupply and return passages extending from freezing compartments, a coldevaporator located in said evaporator compartment, a second evaporatorupon one of the vertical walls in the above freezing compartment, arefrigerant liquefying means operably connected to said evaporators andoperable to cool said cold evaporator to below freezing temperatures andto cool said second evaporator to above freezing temperatures, dampermeans having a first alternate position for shutting oflE communicationbetween said evaporator compartment and said below freezing compartmentand a second position for shutting oif communication between saidevaporator compartment and said above freezing compartment, fan meansfor circulating air through said evaporator compartment and saidpassages and said compartments in accordance with the position of saiddamper means, and control means having one position for operating saidliquefying means to cool said cold evaporator to below freezingtemperatures to cause frost to form thereon and to cool said secondevaporator to above freezing tempera.- tures and setting said dampermeans in said second position and having another position for stoppingthe operation of said liquefying means and setting said damper means insaid first position to cause the circulation of air between said abovefreezing compartment and said evaporator compartment to quickly defrostsaid cold evaporator, a second fan means for circulating air from saidabove freezing compartment into heat transfer with said said evaporatorcompartment to said above and below 30 second evaporator, said controlmeans having means effective in said another position for stopping saidsecond fan means during the defrosting of the cold evaporator.

References Cited in the file of this patent UNITED STATES PATENTS2,812,642 Jacobs Nov. 12, 1957 2,863,300 Murphy et a1. Dec. 9, 19582,866,323 Candor Dec. 30, 1958

